Dilation delivery system for a medical device

ABSTRACT

A kit including a sheath having a tubular body with proximal and distal ends, an axis extending between the ends and a wall defining a bore extending along the axis to the distal end of the body. A delivery tube having proximal and distal ends and a lumen is adapted for disposition within the bore of the sheath in sealing engagement with the sheath, the delivery tube being slideable distally relative to the sheath. An elongated cannula having proximal and distal ends and a lumen is adapted for disposition inside the lumen of the delivery tube and an elongated dilator is adapted to fit within the lumen of the cannula with a proximal portion of the dilator extending proximally beyond the proximal ends of the cannula and delivery tube and in sealing engagement with the delivery tube proximal to the cannula.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/248,356, filed Aug. 2, 2016, which application is related to andclaims the benefit of the filing date of U.S. Provisional PatentApplication No. 62/211,127 filed Aug. 28, 2015, the disclosure of whichis hereby incorporated herein by reference

BACKGROUND OF THE INVENTION

The present invention relates to delivery of medical devices to anoperative site within the body and to systems and methods for the same.

It is often necessary to place medical devices within the body. Forexample, certain mechanical circulatory support devices (“MCSDs”) useinlet cannulas to deliver blood from a chamber of the heart of a patientto a pump implanted within the body at a location remote from the heart.The pump pressurizes the blood and delivers it to an artery, thusassisting the pumping function of the heart. During installation of suchan MCSD, the inlet cannula must be placed so that an end of the cannulaprojects through the wall of the appropriate heart chamber.

It is desirable to perform this procedure with only a minimum ofsurgical disruption to the patient's anatomy. For example, it would bedesirable to install such a cannula through a limited thoracotomy.Although such a cannula can be installed by coring a hole in the wall ofthe heart chamber approximately the diameter of the cannula and thenthreading the cannula into the chamber through the cored hole, such aprocedure requires measures to avoid life-threatening blood loss throughthe hole in the heart wall during installation. Thus, furtherimprovement would be desirable.

SUMMARY OF THE INVENTION

One aspect of the invention provides a kit usable in implanting acannula into a hollow organ. A kit according to this aspect of theinvention desirably includes a sheath having a tubular body withproximal and distal ends and an axis extending between these ends. Thesheath has a wall defining a bore extending along the axis to the distalend of the body and also has an end element disposed at the distal endof the bore. The end element desirably includes a plurality of flapshaving proximal ends attached to the wall of the body at the distal endof the body and also having distal ends remote from the body. The flapsdesirably have a closed position in which the flaps slope inwardlytoward the axis from their proximal ends toward their distal ends, sothat the flaps cooperatively define a surface tapering in the distaldirection beyond the distal end of the body. For example, the flaps maydefine a conical surface. The flaps desirably are displaceable so as tomove the distal ends of the flaps away from the axis and thus pivot theflaps to an open position. The kit according to this aspect of theinvention desirably also includes a delivery tube. The delivery tube hasproximal and distal ends and a lumen. The delivery tube desirably isadapted for disposition within the bore of the sheath, with the deliverytube in sealing engagement with the sheath and slideable relative to thesheath. Desirably, the delivery tube is slideable distally relative tothe sheath from a disengaged position to an engaged position so as toforce the flaps from the closed position to the open position as thedelivery tube moves to the engaged position. The kit desirably alsoincludes an elongated cannula adapted for disposition inside the lumenof the delivery tube and an elongated dilator adapted to fit within thelumen of the cannula. Desirably, the dilator is longer than the cannula,so that when the dilator is received in the cannula, a proximal portionof the dilator extends proximally beyond the proximal ends of thecannula and delivery tube, and this proximal portion desirably is insealing engagement with the delivery tube at a point on the deliverytube proximal to the cannula. Desirably, the flaps of the sheath in theclosed position define a hole at the distal end of the tapered surface,and the dilator has a distal end adapted to project distally beyond thedistal end of the cannula and through the hole.

A further aspect of the invention provides an assembly. The assemblyaccording to this aspect of the invention includes a fluid-tightenclosure defined at least in part by a sheath as discussed above and anelongated cannula contained entirely within the enclosure with thedistal end of the cannula disposed adjacent the distal end of thesheath. An elongated shaft such as the shaft of a dilator as discussedabove desirably is disposed within the lumen of the cannula with aproximal portion of the shaft extending proximally beyond the proximalend of the cannula, the shaft being sealingly engaged with the enclosureand slideable proximally and distally relative to the sheath. Anassembly according to this aspect of the invention may include adelivery tube as discussed above, the proximal portion of the deliverytube in slideable sealing engagement with the sheath and the cannulabeing disposed within the delivery tube. In this embodiment, thedelivery tube forms a portion of the enclosure. The enclosure mayinclude one or more purge ports communicating with the interior of theenclosure and means for sealing the purge ports. As further discussedbelow, an assembly according to this aspect of the invention may be madeusing the elements of the kit discussed in connection with the foregoingaspect of the invention.

Yet another aspect of the invention provides a delivery sheath for amedical device. A delivery sheath according to this aspect of theinvention includes a tubular body having proximal and distal ends, anaxis extending between the ends, and a wall defining an exterior surfaceand a bore extending along the axis to the distal end of the body. Hereagain, an end element is disposed at the distal end of the bore andincludes a plurality of flaps having proximal ends attached to the wallof the body at the distal end of the body and distal ends remote fromthe body, the flaps having a closed position in which the flaps slopeinwardly toward the axis from their proximal ends towards their distalends so that the flaps cooperatively define a surface tapering in thedistal direction beyond the distal end of the body, the flaps beingdisplaceable so as to move the distal ends of the flaps away from theaxis and pivot the flaps to an open position. The sheath according tothis aspect of the invention desirably includes a marker. The markerdesirably includes at least one of the following: (1) a bump projectingoutwardly from the exterior surface of the tubular body; and (2) afeature or features visualizable by fluoroscopic imaging, by ultrasonicimaging, or both, the marker being positioned at the distal end of thebody. A sheath according to this aspect of the invention may beincorporated in the kits and assemblies as discussed above.

Yet another aspect of the present invention includes a kit comprising anelongated cannula having proximal and distal ends, a lumen, and anexterior surface and an expandable anchor mounted to the cannula at thedistal end thereof. Desirably, the anchor is adapted for expansionwithin a hollow organ of a patient's body after insertion of the distalend of the cannula into the organ. The kit according to this aspect ofthe invention desirably includes an external securement device that isdeformable from an open condition to a closed condition and is adaptedto remain in the closed condition after deformation to the closedcondition. The external securement device in the open conditiondesirably is adapted to at least partially surround the outside of thecannula and to slide freely along the cannula. The external securementdevice in the closed condition desirably is adapted to engage theoutside of the cannula as, for example, to frictionally engage and gripthe outside of the cannula. As further discussed below, the elements ofthe kit according to this aspect of the invention may be incorporated ina kit as discussed above or may be used separately.

Yet another aspect of the invention provides methods of connecting acannula to a hollow organ of a patient's body. A method according tothis aspect of the invention desirably includes the step of advancing aliquid-filled enclosure including a sheath having a tapered surfacedefined by a plurality of flaps at the distal end of the sheath, theenclosure entirely containing a hollow cannula having an expandableanchor at its distal end disposed adjacent the distal end of the sheath.The enclosure desirably is advanced in a distal direction toward theorgan until the tapered surface of the sheath passes through the wall ofthe organ. The method desirably further includes the step of bringingthe flaps of the sheath to an open position in which the flaps areseparate from one another and the distal end of the sheath is incommunication with the interior of the organ and advancing the cannuladistally relative to the sheath, so that the anchor is positioned withinthe interior of the organ. The method desirably includes a subsequentstep of expanding the anchor within the interior of the organ andwithdrawing the enclosure proximally, away from the organ while leavingthe cannula in place with the anchor inside the organ and a proximalportion of the cannula projecting from the organ. Desirably, theenclosure includes a delivery tube containing the cannula and theanchor, the delivery tube having an open distal end positioned adjacentthe distal end of the sheath during the step of advancing the enclosurerelative to the organ. The step of expanding the anchor within theinterior of the organ may include advancing the cannula distallyrelative to the delivery tube so that the anchor passes out of thedistal end of the delivery tube. Desirably, the distal end of thedelivery tube is disposed immediately adjacent the flaps of the sheathduring the initial step of advancing the enclosure relative to the organso that upon completion of the initial advancement step, the distal endof the delivery tube is disposed within the interior of the organ. Thestep of bringing the flaps to the open position and advancing thecannula distally relative to the sheath can be performed by withdrawingthe sheath proximally relative to the delivery tube while maintainingthe distal end of the delivery tube in position within the interior ofthe organ.

As further discussed below, kits and methods according to the foregoingaspects of the invention provide simple methods of installing a cannulaand anchoring the same in a hollow organ as, for example, in the atriumof the heart. These and other features and advantages of the presentinvention will be more readily apparent from the detailed descriptionset forth below taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially fragmentary elevational view of a dilatorincorporated in a kit according to one embodiment of the invention.

FIG. 2A is a diagrammatic elevational view of a cannula used in the kitaccording to the embodiment of FIG. 1.

FIG. 2B is a diagrammatic perspective view depicting a portion of thecannula shown in FIG. 2A.

FIG. 3 is a diagrammatic sectional view depicting a delivery tube usedin the kit according to the embodiment of FIG. 1.

FIG. 4A is a diagrammatic sectional view depicting a subassemblyincluding the components depicted in FIGS. 1-3.

FIG. 4B is an elevational view depicting a portions of the cannula shownin FIGS. 2A-2B and the delivery tub of FIG. 3 together with a loadingdevice during formation of the subassembly shown in FIG. 4A.

FIG. 5 is a fragmentary, diagrammatic perspective view of a sheath usedin the kit according to the embodiment of FIG. 1.

FIGS. 6 and 7 are fragmentary, diagrammatic sectional view of the sheathshown in FIG. 5.

FIG. 8 is a fragmentary, diagrammatic sectional view of an assemblyincorporating the components depicted in FIGS. 1-7 at one stage ofoperation.

FIG. 9 is a diagrammatic elevational view of a drive mechanism usable inconjunction with the assembly of FIG. 8.

FIG. 10 is a diagrammatic end elevational view of a securement deviceusable in conjunction with the assembly of FIG. 8.

FIG. 11 is a diagrammatic side elevational view of the securement deviceshown in FIG. 10.

FIG. 12 is a plan view of a forceps usable with the components depictedin FIGS. 1-11.

FIG. 13 is a diagrammatic sectional view of a securement device andcannula according to a further embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic view of a dilator utilized in a kit accordingto one embodiment of the present invention. The dilator 10 includes anelongated shaft 12 having a proximal end 14 and a distal end 16. Thedilator shaft 12 in this embodiment is of generally circularcross-section and may be, for example, about 5-6 mm in diameter. Thedilator shaft has a guidewire lumen 18 extending from the proximal end14 to the distal end 16. The exterior surface of the dilator shaft has aportion 10 tapering in the distal direction. That is, thecross-sectional dimensions of the shaft decrease in the distaldirection, toward distal end 16, over the extent of tapering surface 20.A distal end marker 34, such as a stripe of contrasting color, desirablyis provided adjacent the distal end of the dilator shaft between balloon22 and tapering section 20. A proximal end marker 36 is providedadjacent the proximal end of the shaft. As discussed below, the markersare used to align the other elements of the system during assembly.Either or both of the markers optionally can be radiopaque forfluoroscopic visualization.

A balloon 22 is provided on the dilator shaft near the distal end, butproximal to the tapering surface 20. Balloon 22 may be provided as aunitary balloon completely surrounding the guidewire shaft or a one ormore smaller balloons provided at one or more points around thecircumference of the shaft. Balloon 22 in the deflated conditiondepicted in FIG. 1 projects only slightly from the exterior surface ofthe dilator shaft. When inflated, balloon 22 projects further from theexterior surface of the shaft. An inflation lumen 24 extends from theproximal end 14 of the dilator shaft to balloon 22 and communicates withthe balloon. A fitting 26 has a guidewire port 28 communicating with theguidewire lumen 18 and a separate port 30 communicating with inflationlumen 24, and thus with balloon 22.

During use, a guidewire 32 can be threaded through the guidewire port 28and guidewire lumen 18, so that the guidewire extends entirely throughthe length of the dilator shaft. A syringe (not shown) or other sourceof fluid can be connected to inflation port 30 so that the syringe orother source can be used to selectively inflate and deflate balloon 22.

The dilator shaft desirably is formed from a polymeric material havingsome flexibility but also having substantial stiffness as, for example,a polymer having a hardness in the mid to upper part of the Shore Dscale. The stiffness of the dilator shaft may vary along its length. Forexample, the proximal portion may be stiffer than the distal portion, sothat during implantation the proximal portion will transmitdistally-directed forces readily, and the distal portion will flexreadily to follow a bend in a guidewire. Desirably, the dilator shafthas a hydrophilic surface with a low coefficient of friction. Theballoon desirably has a high coefficient of friction. For example, if alow friction, hydrophilic coating is applied to the dilator shaft, thecoating desirably is no applied to the balloon. Preferably, the dilatorshaft is of constant diameter from its proximal end 14 to taperingsection 20. The dilator shaft may have considerable length as, forexample, twice the length of the cannula 40 discussed below or more; thedilator shaft is shown with portions removed in FIG. 1 for clarity ofillustration.

The kit further includes an elongated cannula 40 (FIGS. 2A, 2B) having aproximal end 42, a distal end 44, and a lumen 46 extending between itsproximal and distal ends. The lumen 46 typically is of constantdiameter. The proximal end 42 of the cannula is of greater outsidediameter than distal end 44. Desirably, the proximal portion of thecannula has progressively decreasing outside diameter in the distaldirection, whereas the distal portion has a constant outside diameter.The distal portion is more flexible than the proximal portion. Thecannula can be formed from a flexible material such as a soft polymerreinforced with a wire winding embedded in the wall of the cannula.

As best seen in FIG. 2B, the cannula further has an expandable anchor 48adjacent its distal end. Anchor 48 desirably includes a central hub 51formed from a rigid material plurality of resilient arms 49 attached tothe hub. In the expanded condition of the anchor depicted in FIGS. 2Aand 2B, the arms project from the cannula transverse to the axis of thecannula. In an assembled, ready-to-use condition of the kit, hereinafterreferred to as the “operative” condition of the kit, the shaft 12 ofdilator 10 is received within the lumen 46 of the cannula, with aproximal portion of the cannula shaft 12 projecting proximally beyondthe proximal end 42 of the cannula and with the distal end 16 and withtapered section 20 projecting distally from the distal end 44 of thecannula. The dilator can be assembled in this position by aligning thedistal end mark 34 on the dilator with the distal end 44 of the cannula.

In this condition, the balloon 22 (FIG. 1) on the dilator is disposedwithin lumen 46. Thus, by inflating the balloon, the balloon can bebrought into forcible engagement with the wall of the cannulasurrounding the lumen 46, so as to lock the cannula and dilatortogether. When the balloon is deflated, the cannula and dilator areslidable proximally and distally relative to one another.

The kit further includes an actuator in the form of a delivery tube 50(FIG. 3). The delivery tube 50 desirably is a thin-walled tube formedfrom a relatively rigid material such as stainless steel. The tube has arounded edge at its distal end 52 and has a fitting 54 at its proximalend 56. The length of delivery tube 50 is slightly greater than thelength of the cannula; a portion of the delivery tube is removed in FIG.3 for clarity of illustration. The delivery tube desirably hashydrophilic interior and exterior surfaces. For example, the tube can becovered with a coating of a hydrophilic material. Delivery tube 50desirably has an interior diameter slightly larger than the maximumexternal diameter of the cannula 40 but smaller than the expandeddiameter of anchor 48. (FIG. 2). For example, the interior diameter ofthe delivery tube may be on the order of 11-12 mm, whereas its wallthickness may be on the order of 0.2 mm, so that the delivery tube hasan external diameter 0.4 mm larger than its internal diameter.

A flexible seal 60 is mounted to fitting 54. The seal may be an O-ringor a hemostatic valve. A purge port 62 extends through the wall of thefitting or through the wall of the delivery tube adjacent its proximalend. Purge port 62 is provided with a fitting 64 such as a Luer fittingfor connection of a liquid source. A plug 65 is detachably mounted infitting 64.

In the assembled operative condition of the kit, the dilator 10, cannula40, and delivery tube 50 form a subassembly depicted in FIG. 4A. In thiscondition, the cannula 40 is disposed entirely within the delivery tube.The distal end 44 of the cannula is disposed proximal to the distal endof the delivery tube. The expandable anchor 48 on the cannula isconfined within the lumen of delivery tube 50. In this condition, theresilient arms constituting the anchor 48 are folded with their endsprojecting distally as shown. Desirably, the ends of the anchor arms 48are also disposed entirely within the interior of the delivery tube. Thedilator 10 projects proximally through the seal 60 at the proximal endof the delivery tube and extends proximally from the delivery tube.Desirably, the shaft of the dilator is in slidable, sealing engagementwith seal 60. The distal end 16 of the dilator projects distally beyondthe distal end of the delivery tube. Most preferably, the taperedsection 20 of the dilator, as well as a small portion of the constantdiameter part of shaft 12, are disposed distal to the delivery tube.

The subassembly shown in FIG. 4 can be made by threading the dilatorthrough the seal of the delivery tube and advancing the dilator distallyrelative to the delivery tube beyond the position illustrated in FIG. 4.The cannula is then placed over the distal end of the dilator andadvanced proximally until the cannula is positioned relative to thedilator as shown in FIG. 2, with the a part of the shaft of the dilatorprojecting out of the distal end of the cannula. When the cannula anddelivery tube are in this position, the distal end mark 34 on thedilator is aligned with the distal end of the cannula. Once the cannulaand dilator are in this position, the balloon 22 of the dilator isinflated so as to lock the cannula to the dilator. The cannula anddilator are then advanced proximally relative to the delivery tube. Aguide 53 (FIG. 4B) may be used during this process. The guide is atubular element open at both ends. A proximal section 55 of the guidehas a bore with an inside diameter just slightly larger than the outsidediameter of the delivery tube, whereas a distal section 57 has a borewith an inside diameter equal to or slightly less than the insidediameter of the delivery tube. The bores of sections 55 and 57 areconcentric with one another. The operator may manually fold the arms 49of anchor 48 to the collapsed condition as shown in FIG. 4B and positionthem within the bore of distal section 55. As the cannula and dilatorare advanced proximally relative to the delivery tube, the delivery tube50 enters the bore of proximal section 55. This aligns the bore of thedistal section 57 concentric with the bore of the delivery tube. As thecannula and dilator are further advanced proximally, the arms 49 of theanchor pass into the delivery tube without catching on the distal edgeof the delivery tube, and without damage to either structure. When thecannula and dilator are properly positioned within the delivery tube,the distal ends of the folded arms 49 of anchor 48 are aligned with orjust proximal to the distal end of delivery tube 50.

To facilitate positioning of the cannula in the delivery tube, thefitting 54 at the proximal end of the delivery tube optionally may beprovided with a stop which abuts the proximal end of the cannula whenthe cannula is properly positioned relative to the delivery tube.Alternatively, the seal 60 carried by the fitting may abut the proximalend of the delivery tube when the cannula is properly positioned.

The kit further includes a delivery sheath 70 (FIGS. 5-8). The deliverysheath has a proximal end 72 (FIGS. 7, 8), a distal end (FIGS. 5, 6, 8),and an axis 76 extending between the proximal and distal ends. Theactuator has a tubular body with a wall 78 surrounding the axis anddefining a bore 80 (FIGS. 6, 7) extending between the proximal anddistal ends. Bore 80 has an interior diameter slightly larger than theexterior diameter of the delivery tube or actuator 50 (FIGS. 4, 8). Forexample, the interior diameter of the bore 80 may be about 12 mm,whereas the exterior diameter of sheath body 78 may be about 12.6 mm.The body desirably is formed from a relatively rigid polymer as, forexample, a polymer of about 63 to about 72 Shore D hardness.

At the proximal end, the sheath 70 has a fitting 82 with a seal 84 (FIG.7) adapted to engage the exterior surface of the delivery tube in asliding, sealing fit. A purge port 86 extends through the wall 78 of thesheath adjacent its proximal end. A sealing plug 87 is releasablyreceived in purge port 86.

At its distal end 74, the sheath includes an end element 90. The endelement includes a plurality of flaps 92 distributed circumferentiallyaround the axis 76 of the sheath. In the depicted embodiment, six flapsare used, of which three are visible in FIG. 5. More or fewer flaps maybe used. In the closed position depicted in FIGS. 5 and 6, the flapsslope inwardly toward axis 76 from their proximal ends toward theirdistal ends, so that the flaps cooperatively define a surface thattapers in the distal direction, beyond the distal end of the body. Thedistal ends 96 of the flaps 92 cooperatively define a hole 100 at thedistal extremity of the end element. This hole is coaxial with the axis76 of the sheath body. In the embodiment depicted, the surface definedby the flaps is substantially in the form of a frustum of a cone, andthe tear lines extend proximally and distally along the conical surface.The sloping surface defined by the flaps desirably lies at an angle A(FIG. 6) of about 10-30° to the axis 76. The end element itself may beformed integrally with the tubular body 78 or may be formed as aseparate part that is joined to the body 78.

In the closed position, the flaps are connected to one another byfrangible elements that releasably hold the flaps in the closedposition. Preferably, the end element is formed as an integral unit froma polymeric material such as, and the frangible elements include simplyweakened portions referred to herein as “tear lines” 98 (FIG. 5) betweeneach paid of mutually adjacent flaps. For example, the tear lines may beformed by scoring inner or outer surface of the unitary element.Desirably, the scores used to form the tear lines extent only partiallythrough the thickness of the end element. During use, the flaps will beforced apart and move to open positions in which the flaps extendgenerally parallel to axis 76, as shown in broken lines at 92′ in FIG.8. During this movement, each flap bends at its proximal end. The endelement may include stress relief features such as circular holes ordepressions (not shown) at the proximal ends of the tear lines 98 tohelp assure that the opening movement does not cause the flaps to breakaway from the wall of the tubular body. The surface formed by the flapspreferably is smooth and is fluid-impervious apart from hole 100. Theflaps be covered by a film (not shown) which extends across the tearlines and covers any holes in the surface, so as to provide the smooth,impervious surface.

The sheath has a bump 102 or projection extending outwardly from theouter surface of body 80 at its distal end, adjacent the juncture withend element 90. This bump may be formed by the end element, by the body,or by an additional material deposited on the exterior of the body. Thebump 102 desirably serves as a marker that can be visualized using animaging modality. For example, where ultrasound is used to image thesheath during the implantation procedure, the bump desirably has anirregular surface pattern that can be discerned on an ultrasound image.Alternatively or additionally, the bump may be radiopaque so that it isvisible in a fluoroscopic image. The sheath may also have one or morevisible markings 104 on its exterior surface at predetermined pointsalong its length.

The sheath, delivery tube, cannula and dilator are diagrammaticallydepicted in FIG. 8 in the assembled, operative condition, ready forimplantation of the cannula within a patient. The subassembly includingthe delivery tube 50, cannula 40 and dilator 10 discussed above withreference to FIG. 4 is received within the sheath 70. The distal end ofthe dilator protrudes through the hole 100 at the distal extremity ofthe end element of the sheath, so that the tapered surface 20 of thedilator is disposed distal to the flaps 92 of the end element. The shaftof the dilator is received within hole 100, with a slight interferencebetween the dilator and the distal ends of the flaps. Desirably, thedilator forms a fluid-tight seal with the end element. The proximal endof the dilator extends proximally beyond the proximally ends of thedelivery tube and sheath. The proximal ends of the sheath and deliverytube are also closed fluid-tight, by seals 84 and 60. Thus, in theoperative condition, cannula 40 is entirely contained within anenclosure defined by the sheath and delivery tube, and that enclosure isfluid-tight, apart from the purge ports on the sheath and delivery tube.In this operative condition, the dilator and cannula are locked togetherby the balloon on the dilator as discussed above with reference to FIG.4. The fitting 54 on the proximal end of the delivery tube 50 is spacedproximally from the fitting 82 of the sheath.

In the operative condition shown in solid lines in FIG. 8, the deliverytube or actuator 50 is disposed in a disengaged position, with thedistal end 52 of the delivery tube disposed proximal to the flaps 92 ofthe end element on the sheath. For example, the delivery tube may be incontact with the flaps. The distal end of the delivery tube is disposedadjacent the bump 102 of the outside of the sheath. In this operativecondition, the fitting 54 on the delivery tube is spaced proximally fromthe fitting 82 on the sheath by a starting distance Ds. This startingdistance should be greater than or equal to the amount of movementrequired to bring the delivery tube to the engaged position discussedbelow. The flaps can be moved from the closed position to an openposition by retracting the sheath 70 relative to the patient whileholding the delivery tube 50 in a fixed position relative to patient, sothat the delivery tube moves distally relative to the sheath. Thismovement continues until the delivery tube is in an engaged positionrelative to the sheath, as partially depicted in broken lines in FIG. 8.

In this engaged position, the distal end of the delivery tube is in theposition indicated at 52′ in FIG. 8. As the sheath moves, the frangibleelements such as score lines break and the flaps 92 are forced to pivotabout their attachments to the body 78 of the sheath, so that the distalends of the flaps move outwardly, away from axis 76 of the sheath. Inthe open position of the flaps, shown in broken lines at 92′ in FIG. 8,the flaps extend generally parallel to the axis. During this movement,the cannula and dilator remain in fixed position with the delivery tube.

Optionally, the dimensions of the delivery tube and sheath may beselected so that the fitting 54 on the delivery tube abuts the fitting82 on the sheath when the delivery tube reaches the engaged position.Thus, the fittings may serve as stops which prevent movement of thedelivery tube beyond its engaged position. This arrangement can be used,for example, where the operator manually moves the sheath during use.

A drive mechanism 110, diagrammatically depicted in FIG. 9, may beprovided for applying moving the sheath relative to the delivery tube.The drive mechanism includes a pair of jaws 112 and 114 adapted toengage the fittings of the delivery tube and sheath. The mechanism alsoincludes an input element such as a handle 116 and a linkage 118connected between the input element and the jaws, the linkage beingarranged to force the jaws toward one another upon movement of the inputelement or handle 116. As depicted in FIG. 9, the mechanism includes aratchet and pawl, and the handle is pivotably mounted to one of thejaws. However, any mechanical linkage which provides a mechanicaladvantage as, for example, a screw or gear mechanism, may be employed.The drive mechanism may include a pre-loaded spring which can bereleased to apply the required force. In a further alternative, thedrive mechanism may include hydraulic, pneumatic or electrically-drivenactuators. The jaws optionally may include features such as slots forreceiving the fittings on the actuator and sheath. Alternatively, thefittings may include recesses and the jaws may include projectionsengagable within the recesses. The drive mechanism may be arranged tomove the sheath through a predetermined distance relative to thedelivery tube. In this case, the fittings on the delivery tube andsheath need not serve as stops, and desirably are spaced apart from oneanother by a starting distance Ds greater than the desired movement.

The kit desirably includes an external securement device 130, depictedin end view in FIG. 10 and in side view in FIG. 11. The securementdevice includes a split ring 132 including an exterior portion 131formed from a stiff polymer and an interior portion 133 formed from asofter polymer. The split ring has a ring axis 134 and a slot 136extending through the ring and extending parallel to the ring axis. Thering has an open condition shown in FIG. 10, in which the slot has afirst width and a closed condition in which the slot has a second widthless than the first width. The securement element includes a latch suchas mating pin 138 and notch 140 on opposite side of the slot. When thesplit ring is in the closed condition, the pin 138 engages in the notch140 and holds the split ring in the closed condition. The dimensions ofthe split ring are selected to that the split ring forms an interferencefit with the section of the cannula 40 near its distal end when the ringis in the closed condition. However, the ring desirably can be forciblymoved along the cannula in the closed condition. The securement device130 also includes a cuff 142 disposed at one end. The cuff is formedfrom a fabric or other material suitable for passage of sutures. Thecuff material desirably is porous and promotes localized clotting andincorporation of cells within the material during the healing process.As explained below, the securement device is applied after placement ofthe cannula into the heart.

The kit may further include a forceps for use in maneuvering the cannulaand the external securement element. The forceps 150 (FIG. 12) includesa pair of arms 152 pivotably relative to one another between the closedposition shown in FIG. 12 and an open position. The arms pivot in aplane of motion parallel to the plane of the drawing in FIG. 12.Proximal ends of the arms are provided with gripping rings 154. Thedistal ends of the arms are curved out of the plane of motion, and areprovided with jaws 156. Each jaw is defines a generally U-shaped channelso that when the jaws are in the closed position as depicted, theycooperatively define at least a portion of a tubular channel having anaxis extending parallel or nearly parallel to the plane of motion of thearms. The channel desirably is sized to grasp the outside diameter ofthe distal portion of the cannula, but not to crush the cannula so as todamage it. The jaws are spaced from the plane of the arms 152 so thatthe axis 158 of the tubular channel defined by jaws 156 is spaced fromthe plane of arms 152. In an open position of the arms, the jaws arespaced apart from one another.

One sequence of operations which can be used to implant a cannula into apatient using the kit discussed above with reference to FIGS. 1-11 is asfollows:

A small opening is formed in the patient's chest to expose the externalsurface of the heart at the desired chamber of the heart as, forexample, the left atrium. A needle is inserted through the wall of thechamber, and a guidewire is inserted into the chamber. The guidewire mayhave a marking to indicate the desired depth of insertion. The needle isremoved, leaving the guidewire in place with a proximal end of theguidewire extending out of the heart.

The assembly of the sheath, delivery tube, cannula and dilator, in theoperative condition shown in FIG. 8, is flushed with saline solution byintroducing the solution through the flushing port 64 (FIG. 3) of thedelivery tube and allowing air to escape through the flushing port 86 ofthe sheath. These ports may then be closed by plugs 65 and 87. Thesealed enclosure provided by the sheath and delivery tube allows theassembly to be flushed before it is brought into proximity to thepatient. The assembly is “back-loaded” onto the guidewire, by threadingthe proximal end of the guidewire proximally through the guidewire lumen18 (FIG. 1) of the dilator and through the guidewire port 28.

The entire assembly is manually advanced along the guidewire. As thedistal end of the dilator penetrates the wall of the heart, the taperedsurface 20 of the dilator (FIGS. 1, 8) forces the heart wall tissueoutwardly, away from the axis. With continued advance of the assembly,the tapered surface defined by the flaps 92 of the end element on thesheath further forces the tissue outwardly, away from the axis 76 of thesheath. When the bump 102 (FIG. 6) on the distal end of the sheathpasses through the wall of the heart, resistance to the advancedecreases. This provides an indication to the operator that the assemblyis correctly positioned. The positioning also may be confirmed byimaging, and by observing the position of the depth mark 104 (FIG. 5) onthe sheath relative to the exterior of the heart.

At this point in the procedure, the flaps 92 of the end element on thesheath are disposed inside the heart chamber. Moreover, the distal endof the delivery tube is positioned inside the heart chamber. The flapsare then brought to the open position, preferably by retracting thesheath proximally relative to the heart, while maintaining the positionof the delivery tube relative to the heart. The drive mechanism (FIG.10) can be used to impel this motion.

After the flaps of the end element have been brought to their openposition (92′, FIG. 8) the cannula 40 can be advanced distally relativeto the delivery tube 50 and sheath 70 by moving the dilator distallyrelative to those elements. Because the dilator is locked to the cannulaby the balloon as discussed above, the cannula will move along with thedilator. When mark 36 on the dilator is aligned with the fitting 54 onthe proximal end of the delivery tube, the distal end of the cannula 40has advanced beyond the distal end of the delivery tube. Thispositioning can be confirmed by ultrasonic or other imaging. The arms ofanchor 48 spring out to their expanded position (FIGS. 2A and 2B), sothat the anchor will retain the distal end of the cannula within theheart.

While continuing to maintain the balloon on the dilator in its inflatedstate, so that the dilator remains locked to the cannula, the operatormanually retracts the delivery tube 50 and sheath 70 proximally alongthe dilator, until they are proximal to distal section of the cannulathe cannula. As the delivery tube and sheath are retracted, the heartwall closes around the cannula proximal to the anchor, forming asubstantial tissue seal around the cannula. After retracting thedelivery tube and sheath, the operator can grasp the cannula, eitherwith his or her hands or with forceps 150 (FIG. 12), or both.

The operator can slip the external securement device 130 over the distalsection of the cannula by passing holding the split ring 132 in the jawsof forceps 150, with the slot 136 (FIG. 12) of the split ring open, andmoving the slot over the cannula transverse to its axis, until thecannula is inside the split ring. The operator can then close the splitring by moving the arms of the forceps toward the closed position. Thesplit ring is placed on the cannula so that the cuff 142 faces towardthe heart. Before or after closing the split ring, the operator canadvance the split ring along the cannula until the cuff touches the wallof the heart. The operator may also suture the cuff to the heart wall.The offset between the jaws of forceps 150 and the plane of motion ofthe arms of the forceps keeps the arms of the forceps, and theoperator's hand manipulating the forceps, out of the operator's line ofsight and thus allows the operator to see the distal section of thecannula and the split ring during this process. Also, thepartially-retracted sheath and delivery tube support and stabilize thecannula during this process. Once the external securement device 130 isin place, the wall of the organ is secured between the expanded anchor48 engaging the interior of the heart wall and the external securementdevice on the exterior of the heart wall, so that cannula 40 is held inposition. The operator then deflates the balloon on the dilator, therebyunlocking the dilator from the cannula, and retracts the dilator out ofthe cannula, carrying the sheath and delivery tube out of the way. Theoperator plugs the proximal end of the lumen in the cannula using a plug(not shown) to prevent blood loss.

The anchor on the cannula and the external locking device hold thedistal end of the cannula in place. The proximal end of the cannula canbe threaded though the patient's body to the location where the pump ofthe MCSD is to be placed, and connected to the pump. This is typicallydone by pulling the proximal end through a surgically-formed tunnelusing a tool connected to the proximal end. For example, the pluginserted in the proximal end may have screw threads or otherconventional features for engaging the pulling tool.

Numerous variations of the features discussed above can be used. Forexample, in the embodiment described above, the end element 90 in theclosed position (FIG. 5) defines a conical surface with no openingsapart from the central opening 100. This is highly desirable tofacilitate purging of the system, but not essential in thoseapplications where complete purging is not required. For example, theremay be gaps between adjacent flaps when the flaps are in the closedposition. Also, the flaps of the end element may be formed separatelyfrom one another. A frangible element used to hold the flaps in theclosed position may be formed separately from the flaps. In a furthervariant, a release element such as a suture having an end accessible tothe operator near the proximal end of the sheath may hold the flapsclosed. The operator may operate the release element, as by pulling thesuture out before bringing the flaps to the open position. In such anarrangement, the flaps optionally may be resiliently biased to the openposition, so that they will move to the open position when the releaseelement is removed. With this variant, the actuator or delivery tube isnot required. In yet another variant, the flaps may be resilientlybiased to the closed position, and may be forced to the open position bythe actuator. The surface defined by the flaps need not be in the formof a cone or part of a cone; the surface may have a non-uniform taper.Also, in the embodiment above, the sheath, delivery tube, cannula anddilator all have generally circular cross-sectional shapes, butnon-circular shapes may be employed.

In the embodiments above, the actuator used to move the flaps is thetube 50. However, the actuator need not be tubular. For example,individual rods may extend lengthwise within the sheath, each such rodbeing linked to one flap. The rods may be linked to one another, or maybe individually movable by the operator. In any such arrangement, thesurfaces surrounding the anchors on the cannula desirably are smooth sothat the anchors will not be damaged and will deploy smoothly. In yetanother variant, the actuator may be omitted and other means may be usedto move the flaps to the open position. For example, an additionalballoon can be placed around the distal end of the dilator, so that theadditional balloon is disposed distal to the cannula, inside the endelement. Such a balloon can be inflated momentarily to open the flapsand then deflated.

The dilator 10 used in the embodiments discussed above is not essential.For example, flaps 92 of the end element of the sheath may form asurface which tapers to a point, with no central opening or with only avery small opening for a guidewire.

The device placed using the kit need not be a cannula as discussedabove. Any other device can be placed. For example, certain MCSDs usepumps which can be placed partially or fully within a chamber of theheart. A pump of this type can be positioned within the sheath andplaced using the device. Also, the device may be placed into holloworgans other than the heart.

In the embodiments discussed above, a balloon on the dilator serves toreleasably lock the dilator and cannula together. However, otherstructures which can perform this function may be employed. For example,the dilator may be provided with a mechanical element such as a basketwhich can be expanded and contracted using a control element accessibleat the proximal end of the dilator.

In the embodiments discussed above, the external securement device 130is placed on the cannula after the cannula has been implanted, as bypassing the slot 136 of the split ring (FIG. 10) over the cannula. In afurther variant, the external securement device may be disposed on thecannula, remote from the distal end of the cannula, before the cannulais implanted. In such an arrangement, the external securement device maybe a simple closed ring 230 (FIG. 13). In the open condition shown insolid lines, ring 230 has an inside diameter slightly larger than theoutside diameter of the cannula 240, so that the ring forms afree-running fit with the cannula at least near the distal end. Wherethe cannula has a tapered outside diameter, the ring in the opencondition may frictionally engage the cannula at its larger, proximalend, so that the ring will remain in place during implantation. The ringcan be deformed to the closed position shown in broken lines by crimpingthe ring, using a forceps or similar instrument. In the closed position,the ring will engage the distal end of the cannula with a tight fit. Forexample, the ring may be formed from a material which can be plasticallydeformed in the transition from the open condition to the closedcondition. In further variants, the cannula may have a series of ridges(not shown) projecting outwardly on its exterior surface adjacent itsdistal end, and the external securement device may have correspondingridges on its interior surface. In this embodiment, the ridges on thecannula mechanically engage with the ridges on the external securementdevice when the external securement device is brought to the closedposition. External securement devices as described herein can be usedwith a cannula regardless of how the distal end of the cannula isimplanted in the organ of the subject.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention. Certain aspects of the present invention arefurther described in the appended claims.

INDUSTRIAL APPLICABILITY

The present invention can be applied in medical and veterinarytreatment.

The invention claimed is:
 1. A method of connecting a cannula to ahollow organ of a patient's body comprising the steps of: advancing aliquid-filled enclosure including a sheath having a tapered surfacedefined by a plurality of flaps at the distal end of the sheath, thesheath containing a hollow cannula having an expandable anchor at itsdistal end disposed proximate the distal end of the sheath, in a distaldirection towards the organ until the tapered surface passes through thewall of the organ; bringing the flaps of the sheath to an open positionin which the flaps are separate from one another and the distal end ofthe sheath is in communication with the interior of the organ andadvancing the cannula distally relative to the sheath so that the anchoris positioned within the interior of the organ; expanding the anchorwithin the interior of the organ; and withdrawing the sheath proximallyaway from the organ while leaving the cannula in place with the anchorinside the organ and a proximal portion of the cannula projecting fromthe organ; and the sheath includes a delivery tube containing thecannula and anchor, the delivery tube having an open distal endpositioned adjacent the distal end of the sheath, and the method furtherincludes advancing the cannula distally relative to the delivery tube sothat the anchor passes out of the distal end of the delivery tube. 2.The method of claim 1, wherein the distal end of the delivery tube isdisposed within the interior of the organ upon completion of theadvancing step, and wherein the method further includes withdrawing thesheath proximally relative to the delivery tube while maintaining thedistal end of the delivery tube within the interior of the organ.
 3. Themethod of claim 2, wherein the step of advancing the cannula relative tothe delivery tube includes advancing a shaft disposed within theinterior of the cannula and projecting proximally from the delivery tubewhile the cannula is locked to the shaft, the method further includingthe step of unlocking the cannula from the shaft.
 4. The method of claim3, wherein the withdrawing step further includes withdrawing the sheathproximally along the shaft while holding the shaft in position relativeto the organ before unlocking the cannula from the shaft.
 5. The methodof claim 4, wherein the shaft is a portion of a dilator, the dilatorincluding a tip having a tapered surface at the distal end of the shaft,the tip of the dilator projecting distally from the tapered surface ofthe sheath during the advancing step.